Throughout the vast majority of English speaking countries around the world bicycle gears are typically measured in the imperial measurement of inches and calculating the effective gear of a bicycle in inches dates back to the times of old ordinary cycles. On these bikes the pedals were permanently fixed to the larger front wheel so if you had to go faster you just pedaled more rapidly. Not all of the wheels were a matching size though so they were assessed by their diameter. A sixty inch wheel diameter on a penny farthing could be fast but it meant that the bike would be massive to accommodate it so only a larger strong rider could hope to ride it.While you might not need to learn exactly what these inch measurements necessarily mean you will most likely want to be aware that a lower number of inches, commonly known as a lower gear, is easier to drive the pedals on a regular bicycle, than a higher gear comprised of a larger number of inches that would require more force to move the pedals around. By and large lower gears are usually used to go uphill, albeit at a lower speed while higher gears are useful for the flats aided by the wind behind you and for downhill sections.
When bicycle design and style altered toward the more regular bikes that we now recognise by their diamond shaped construction their wheels were a lot smaller and the pedals were linked to the wheel through a chain and gearing system. A larger chainwheel and a smaller rear sprocket would enlarge the gear so for example a 32 teeth chain wheel with a 16 tooth sprocket, as fitted to countless singlespeed all terrain bikes these days, would turn the rear wheel through two revolutions for every one turn of the pedals. With a mountain bike wheel generally having a 26 inch diameter that would equate to an effective gear of 52 inches on a bicycle that is almost certainly a lot less difficult to operate than an old penny farthing with a wheel diameter of 52 inches.
To work out gear size you must know the diameter of your rear wheel, and the amount of teeth on the chainring and the rear cog. You can then complete the following formula: Gear in inches = number of teeth on chainring x wheel diameter in inches / number of teeth on the rear cog. It's worth noting that depending on what size tyres are fitted the diameter of your wheel will change. For example a 1 inch slick tyre fitted to a MTB wheel has a smaller diameter than a 2.5inch knobbly tyre on the same wheel. It's also worth noting that should you need to calculate the distance that your bike will cover as a result of one rotation of the pedals you will need to work out the circumference of the wheel from the diameter. To do this you have to multiply the diameter of the wheel by PI or 3.14 and you'll know how many pedal turns it will require to cover a given distance.
If the calculation looks daunting you can use the virtual bicycle gear calculator which also has the diameters of most common wheel and tyre set-ups built in for extra precision.
Clive Armstrong is a well known author and advisor on all matters pertaining to bicycles and cyclesport.
When bicycle design and style altered toward the more regular bikes that we now recognise by their diamond shaped construction their wheels were a lot smaller and the pedals were linked to the wheel through a chain and gearing system. A larger chainwheel and a smaller rear sprocket would enlarge the gear so for example a 32 teeth chain wheel with a 16 tooth sprocket, as fitted to countless singlespeed all terrain bikes these days, would turn the rear wheel through two revolutions for every one turn of the pedals. With a mountain bike wheel generally having a 26 inch diameter that would equate to an effective gear of 52 inches on a bicycle that is almost certainly a lot less difficult to operate than an old penny farthing with a wheel diameter of 52 inches.
To work out gear size you must know the diameter of your rear wheel, and the amount of teeth on the chainring and the rear cog. You can then complete the following formula: Gear in inches = number of teeth on chainring x wheel diameter in inches / number of teeth on the rear cog. It's worth noting that depending on what size tyres are fitted the diameter of your wheel will change. For example a 1 inch slick tyre fitted to a MTB wheel has a smaller diameter than a 2.5inch knobbly tyre on the same wheel. It's also worth noting that should you need to calculate the distance that your bike will cover as a result of one rotation of the pedals you will need to work out the circumference of the wheel from the diameter. To do this you have to multiply the diameter of the wheel by PI or 3.14 and you'll know how many pedal turns it will require to cover a given distance.
If the calculation looks daunting you can use the virtual bicycle gear calculator which also has the diameters of most common wheel and tyre set-ups built in for extra precision.
Clive Armstrong is a well known author and advisor on all matters pertaining to bicycles and cyclesport.
评论
发表评论